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Flightless Friday - Rhea americana Edition

These rheas aren’t the greatest, they’re just greater.

The Greater Rhea (Rhea americana) is the largest bird in South America, and can be found primarily in Brazil, Argentina, Paraguay, Bolivia and Uruguay. It prefers habitats with open spaces, like grasslands, wetlands or savanna. Other names for the Greater Rhea include the common rhea, the gray rhea, ñandú, ema and the American rhea. Interestingly, there is a small wild population of Greater Rhea in Germany, which started when a male and five females escaped from a farm and got down to the business of reproduction. They’ve survived the winters and as of 2012 there were about 100 of them. The group has established territory in Nordwestmecklenberg.


Greater Rhea stand about 4.9 feet (1.5 meters) tall, and they weigh about 60 pounds (27 kg). Males are generally bigger than females, but they have the same color plumage, which is gray-brown. They have long, strong legs and long wings for a flightless bird. Greater Rheas spread their wings to help them balance while running, and also to communicate. The Greater Rhea pictured above is trying to create a distraction to lead potential threats away from his nest. They can run up to 37 miles per hour (60 km/h), and are surprisingly good swimmers.

The diet of the Greater Rhea is mostly made up of vegetation, like broad-leaf foliage, tubers, seeds and fruit. They will also eat insects, arachnids, reptiles, small birds and mammals. Greater Rhea will also swallow small pebbles to aid in digestion, and they are attracted to shiny objects and will often swallow those as well, even if they’re made of glass or metal.


There are currently five recognized subspecies of Greater Rhea:

  • Rhea americana americana (northeastern Brazil)
  • Rhea americana intermedia (Uruguay)
  • Rhea americana nobilis (Paraguay)
  • Rhea americana araneipes (Bolivia)
  • Rhea americana albescens (Argentina)

Greater Rhea form large flocks outside of the breeding season, which can range in size from 10 to 100 birds. When the breeding season starts in August, they split up into smaller gendered groups, with females hanging out together and males becoming territorial with each other. The males try to attract the groups of females into his territory so that he can mate with them, and all of the females will lay their eggs in the nest that he prepares. There are usually 20 to 30 eggs that are laid by the females in the group, although some nests have held up to 80! The males incubate the eggs for 40 days and cares for the chicks for the next six months, while they attain almost their full growth.


Adult Greater Rhea are preyed upon by large cats like cougars and jaguars. Young Greater Rhea are often killed by feral dogs, and various armadillo feed on the eggs. Greater Rhea are farmed for meat, skin and feathers, and cannot usually survive in the wild if they are raised in captivity. It is considered to be near threatened by the IUCN.

Source for all images used in this post.

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